This nonprovisional application claims priority under 35 U.S.C. xc2xa7 119(a) on patent application Ser. No. 2002-078338 filed in Japan on March 20, 2002, which is herein incorporated by reference.
1. Field of the Invention
The present invention relates to an image signal generating apparatus that causes a plurality of display units each having their own identification data to display individual images, an image signal generating method that is implemented by the aforementioned image signal generating apparatus, a program for causing a computer system to implement the aforementioned image signal generating method, and a computer-readable information storage medium that contains the aforementioned program.
2. Description of the Related Art
The Japanese Patent Kokai (Laid-Open) Publication No. 2000-352962 published on Dec. 19, 2000 discloses a system wherein a single image signal generating apparatus (e.g., a personal computer) causes a plurality of display units (e.g., CRT monitors or liquid crystal monitors) to display individual images. The display units used in the system hold their own identification data (e.g. their own identification numbers (ID Nos. or Unit Nos.)) respectively. The image signal generating apparatus used in the system transmits an image signal for each frame including an index signal to all the display units connected thereto.
Each of the display units judges whether or not the index signal added to the received image signal for each frame coincides with its own identification data. The display unit that has an identification data coinciding with the index signal, displays an image based on the image signal for each frame having the index signal (that is, the display unit rewrites the contents of its image memory). On the other hand, the display unit that has an identification data not coinciding with the index signal, ignores the received image signal for each frame having the index signal and does not change the displaying image (that is, the display unit does not change the contents of its image memory).
In this system, the plurality of display units that receive the same image signal transmitted from a single image signal generating apparatus can display an image in a time division manner (e.g., by changing an index signal to be added to the image signal for each frame whenever a predetermined number of frame periods has passed) or selectively (e.g., on the display unit selected by the user). As a result, only by connecting the single image signal generating apparatus with the plurality of display units by means of a connection cable or cables, a single image can be displayed on a broad area made up of the display regions of the plurality of display units, or a plurality of windows to be displayed based on the application software can be displayed on the respective display regions of the plurality of display units.
In the aforementioned conventional system, however, when the individual images each including a mouse pointer are displayed on the respective display regions of the plurality of display units, the mouse pointers 51 and 51a are displayed on all the display units 11, 12 and 13 respectively, as shown in FIG. 11. For this reason, it is difficult for the user to draw a distinction between the mouse pointer 51 and the mouse pointers 51a, wherein the mouse pointer 51 (movable by a mouse operation) is displayed on the display unit (which is one of the display units selected by the index signal and corresponds to the display unit 12 in FIG. 11) based on the image signal being received from the image signal generating apparatus, and the mouse pointers 51a (immovable by a mouse operation) are displayed on the display units (which correspond to the display units 11 and 13 in FIG. 11) based on the data remaining in the respective image memories of the display units.
It is an object of the present invention to provide an apparatus, method, and program for generating an image signal that permits displaying a pointer on only a selected one of display units, and a computer-readable information storage medium containing the aforementioned program.
According to an aspect of the present invention, an image signal generating apparatus which transmits an image signal to a plurality of display units each having identification data, includes an image signal generator which sequentially generates an image signal for each frame that is an image signal for displaying one page image in one frame period, the one page image being an image to be displayed on each of the plurality of display units; an indexer which adds an index signal to the image signal for each frame; and a pointer controller which controls addition or non-addition of a pointer signal to the image signal for each frame, the pointer signal being a signal for displaying a pointer on each of the plurality of display units. The image signal generating apparatus also includes an image signal output circuit which sequentially transmits the image signal for each frame to the plurality of display units, thereby causing any of the plurality of display units having identification data corresponding to the index signal added to the transmitted image signal for each frame to display an image based on the transmitted image signal for each frame; and a central controller which controls the pointer controller in such a way that the pointer signal is not added to the image signal for each frame during at least one frame period from a first time point that is at least one frame period previous to a second time point at which the display unit for displaying the one page image based on a received image signal is changed by changing the index signal added to the image signal for each frame.
According to another aspect of the present invention, an image signal generating apparatus which transmits an image signal to a plurality of display units each having identification data, includes an image signal generator which sequentially generates an image signal for each frame that is an image signal for displaying one page image in one frame period, the one page image being an image to be displayed on each of the plurality of display units; an indexer which adds an index signal to the image signal for each frame; and a pointer controller which controls addition or non-addition of a pointer signal to the image signal for each frame, the pointer signal being a signal for displaying a pointer on each of the plurality of display units. The image signal generating apparatus also includes an image signal output circuit which sequentially transmits the image signal for each frame to the plurality of display units, thereby causing any of the plurality of display units having identification data corresponding to the index signal added to the transmitted image signal for each frame to display an image based on the transmitted image signal for each frame; and a central controller which controls the indexer and the pointer controller. The central controller controls the indexer in such a way that the index signal is changed to an invalid index signal corresponding to none of the identification data of the plurality of display units during at least one frame period from a first time point that is at least one frame period previous to a second time point at which the display unit for displaying the one page image based on a received image signal is changed by changing the index signal added to the image signal for each frame. The central controller controls the pointer controller in such a way that the pointer signal is not added to the image signal for each frame during at least one frame period from a third time point that is at least one frame period previous to the first time point.
According to a further aspect of the present invention, an image signal generating method for transmitting an image signal to a plurality of display units each having identification data, includes sequentially generating an image signal for each frame that is an image signal for displaying one page image in one frame period, the one page image being an image to be displayed on each of the plurality of display units; adding an index signal to the image signal for each frame; and controlling addition or non-addition of a pointer signal to the image signal for each frame, the pointer signal being a signal for displaying a pointer on each of the plurality of display units. The image signal generating method also includes sequentially transmitting the image signal for each frame to the plurality of display units, thereby causing any of the plurality of display units having identification data corresponding to the index signal added to the transmitted image signal for each frame to display an image based on the transmitted image signal for each frame; and controlling the pointer controller in such a way that the pointer signal is not added to the image signal for each frame during at least one frame period from a first time point that is at least one frame period previous to a second time point at which the display unit for displaying the one page image based on a received image signal is changed by changing the index signal added to the image signal for each frame.
According to a further aspect of the present invention, an image signal generating method for transmitting an image signal to a plurality of display units each having identification data, includes sequentially generating an image signal for each frame that is an image signal for displaying one page image in one frame period, the one page image being an image to be displayed on each of the plurality of display units; adding an index signal to the image signal for each frame; and controlling addition or non-addition of a pointer signal to the image signal for each frame, the pointer signal being a signal for displaying a pointer on each of the plurality of display units. The image signal generating method also includes sequentially transmitting the image signal for each frame to the plurality of display units, thereby causing any of the plurality of display units having identification data corresponding to the index signal added to the transmitted image signal for each frame to display an image based on the transmitted image signal for each frame; controlling the indexer in such a way that the index signal is changed to an invalid index signal corresponding to none of the identification data of the plurality of display units during at least one frame period from a first time point that is at least one frame period previous to a second time point at which the display unit for displaying the one page image based on a received image signal is changed by changing the index signal added to the image signal for each frame; and controlling the pointer controller in such a way that the pointer signal is not added to the image signal for each frame during at least one frame period from a third time point that is at least one frame period previous to the first time point.
According to a further aspect of the present invention, a computer-readable information storage medium contains a program for causing a computer system to perform an image signal processing, wherein the computer system transmits an image signal to a plurality of display units each having identification data, and the computer system includes an image signal generator which sequentially generates an image signal for each frame that is an image signal for displaying one page image in one frame period, the one page image being an image to be displayed on each of the plurality of display units. The image signal processing includes adding an index signal to the image signal for each frame; and controlling addition or non-addition of a pointer signal to the image signal for each frame, the pointer signal being a signal for displaying a pointer on each of the plurality of display units. The image signal processing also includes sequentially transmitting the image signal for each frame to the plurality of display units, thereby causing any of the plurality of display units having identification data corresponding to the index signal added to the transmitted image signal for each frame to display an image based on the transmitted image signal for each frame; and controlling in such a way that the pointer signal is not added to the image signal for each frame during at least one frame period from a first time point that is at least one frame period previous to a second time point at which the display unit for displaying the one page image based on a received image signal is changed by changing the index signal added to the image signal for each frame.
According to a further aspect of the present invention, a computer-readable information storage medium contains a program for causing a computer system to perform an image signal processing, wherein the computer system transmits an image signal to a plurality of display units each having identification data, and the computer system includes an image signal generator which sequentially generates an image signal for each frame that is an image signal for displaying one page image in one frame period, the one page image being an image to be displayed on each of the plurality of display units. The image signal processing includes adding an index signal to the image signal for each frame; controlling addition or non-addition of a pointer signal to the image signal for each frame, the pointer signal being a signal for displaying a pointer on each of the plurality of display units; and sequentially transmitting the image signal for each frame to the plurality of display units, thereby causing any of the plurality of display units having identification data corresponding to the index signal added to the transmitted image signal for each frame to display an image based on the transmitted image signal for each frame. The image signal processing also includes controlling in such a way that the index signal is changed to an invalid index signal corresponding to none of the identification data of the plurality of display units during at least one frame period from a first time point that is at least one frame period previous to a second time point at which the display unit for displaying the one page image based on a received image signal is changed by changing the index signal added to the image signal for each frame; and controlling in such a way that the pointer signal is not added to the image signal for each frame during at least one frame period from a third time point that is at least one frame period previous to the first time point.
According to a further aspect of the present invention, a program causes a computer system to perform an image signal processing, wherein the computer system transmits an image signal to a plurality of display units each having identification data, and the computer system includes an image signal generator which sequentially generates an image signal for each frame that is an image signal for displaying one page image in one frame period, the one page image being an image to be displayed on each of the plurality of display units. The image signal processing includes adding an index signal to the image signal for each frame; and controlling addition or non-addition of a pointer signal to the image signal for each frame, the pointer signal being a signal for displaying a pointer on each of the plurality of display units. The image signal processing also includes sequentially transmitting the image signal for each frame to the plurality of display units, thereby causing any of the plurality of display units having identification data corresponding to the index signal added to the transmitted image signal for each frame to display an image based on the transmitted image signal for each frame; and controlling in such a way that the pointer signal is not added to the image signal for each frame during at least one frame period from a first time point that is at least one frame period previous to a second time point at which the display unit for displaying the one page image based on a received image signal is changed by changing the index signal added to the image signal for each frame.
According to a further aspect of the present invention, a program causes a computer system to perform an image signal processing, wherein the computer system transmits an image signal to a plurality of display units each having identification data, and the computer system includes an image signal generator which sequentially generates an image signal for each frame that is an image signal for displaying one page image in one frame period, the one page image being an image to be displayed on each of the plurality of display units. The image signal processing includes adding an index signal to the image signal for each frame; controlling addition or non-addition of a pointer signal to the image signal for each frame, the pointer signal being a signal for displaying a pointer on each of the plurality of display units; and sequentially transmitting the image signal for each frame to the plurality of display units, thereby causing any of the plurality of display units having identification data corresponding to the index signal added to the transmitted image signal for each frame to display an image based on the transmitted image signal for each frame. The image signal processing also includes controlling in such a way that the index signal is changed to an invalid index signal corresponding to none of the identification data of the plurality of display units during at least one frame period from a first time point that is at least one frame period previous to a second time point at which the display unit for displaying the one page image based on a received image signal is changed by changing the index signal added to the image signal for each frame; and controlling in such a way that the pointer signal is not added to the image signal for each frame during at least one frame period from a third time point that is at least one frame period previous to the first time point.